Period 3 - Conservation of Energy Practice

PowerPoint Presentation

Question of the Day

The answer is B.

This question is taken from paper 11 of May/June 2012.

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Question of the Day

The answer is B.

This question is taken from paper 11 of May/June 2012.

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Todays Objectives:

You will be able to trace the movement of energy through examples involving multiple stages.You will be able to identify where and when energy is dissipated.

The Law of Conservation of EnergyThe total energy of an isolated system remains constant.Energy can be neither created nor destroyed.Energy can transform from one form to another.

This slide is review from the previous class demonstration. Energy lost to heat (including air resistance) and sound can be introduced as internal energy or energy dissipated.

Image from:http://www.eoht.info/page/Conservation+of+energy

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Conservation of EnergyA wind-up toy is fully wound and at rest.

Gravitational Potential EnergyElastic EnergyKinetic EnergyInternal Energy(Dissipated to Heat & Sound)

This slide introduces Energy Pie Charts as a way to show the energy in a system at different stages. There should only be elastic energy in the system.

Image from:https://modelinginstruction.org/

Video from:https://www.youtube.com/watch?v=JFMeWe8TAds5

Conservation of EnergyA wind-up toy is fully wound and at rest.

Gravitational Potential Energy Elastic EnergyKinetic EnergyInternal Energy(Dissipated to Heat & Sound)

This slide introduces Energy Pie Charts as a way to show the energy in a system at different stages. There should only be elastic energy in the system.

Image from:https://modelinginstruction.org/

Video from:https://www.youtube.com/watch?v=JFMeWe8TAds6

Conservation of EnergyA wind-up toy is wound up and moving across level ground. The toy is speeding up.

A B C D E

Gravitational Potential Energy Elastic EnergyKinetic EnergyInternal Energy(Dissipated to Heat & Sound) A B C D E

This slide builds on the previous one, adding multiple stages and kinetic energy to the problem. Instruct the students to ignore energy lost to heat (friction) and sound.

Image from:https://modelinginstruction.org/7


A B C D E

Elastic EnergyKinetic EnergyInternal Energy(Dissipated to Heat & Sound)

A B C D E

This is not the only answer (see below). Discuss other possible scenarios and then ask what it would look like with internal energy.

The model should show:- Kinetic energy increases.- Elastic energy decreases.- No internal energy at any stage.

Accept:- Still elastic energy at the fifth stage.- A small quantity of kinetic energy at the first stage.



A B C D E


A B C D E

This is a possible answer.

The model should show:- Kinetic energy increases.- Elastic energy decreases.- No internal energy at first stage, internal energy never decreases.- Internal energy increases.

Accept:- Still elastic energy at the fifth stage.- A small quantity of kinetic energy at the first stage.


Conservation of EnergyThe toy is wound up and is moving at a constant speed up an incline.

A B C D E

Gravitational Potential EnergyElastic EnergyKinetic EnergyInternal Energy(Dissipated to Heat & Sound) A B C D E

This slide builds on the previous ones, adding gravitational potential energy to the problem. The teacher can decide to include or exclude energy lost to heat (friction) and sound.


Conservation of EnergyThe toy is wound up and is moving at a constant speed up an incline.

A B C D E


A B C D E


The model should show:- Kinetic energy is at each stage, and it remains constant.- Gravitational potential energy increases by even intervals.- Elastic energy decreases.- No internal energy at first stage, internal energy never decreases.- Internal energy increases.

Accept:- Still elastic energy at the last stage.- Some gravitational potential energy at the first stage.- Different quantity of kinetic energy at each stage, as long as it is constant.- Students do not include internal energy if not instructed to do so.


Conservation of EnergyThe toy is wound up and moving along at a constant speed.

A B C D E


The students are given small whiteboards and markers. They can be instructed to work in groups or alone. As they work, the teacher circulates the room and asks the student to discuss their energy pie charts. Afterward, a student can be asked to stand and share how they drew their energy pie charts and why. Other students can share how and why they completed their charts differently.


Conservation of EnergyThe toy is wound up and moving along at a constant speed.

A B C D E


A B C D E


The model should show:- Kinetic energy is at each stage and it remains constant.- Elastic energy decreases.- No internal energy at first stage, internal energy never decreases.- Internal energy increases.

Accept:- Still elastic energy at the fifth stage.- Different quantities of kinetic energy at each stage than the example, as long as they are constant.


Conservation of EnergyThe toy is wound up and slowing down as it moves up an incline.

A B C D E


The teacher will not have time to complete all of the sample problems below. They can pick which ones to use based on student progress.

The students continue to create energy pie charts for situations. As they work, the teacher circulates the room and asks the student to discuss their energy pie charts. Afterward, a student can be asked to stand and share how they drew their energy pie charts and why. Other students can share how and why they completed their charts differently.


Conservation of EnergyThe toy is wound up and slowing down as it moves up an incline.

A B C D E


A B C D E


The model should show:- Kinetic energy decreases.- Gravitational potential energy increases, it can be proportional to the changes in heights.- Elastic energy decreases.- No internal energy at first stage, internal energy never decreases.- Internal energy increases.

Accept:- Still elastic energy at the fifth stage.- Some gravitational potential energy at the first stage.- No kinetic energy at the fifth stage.- Students do not include internal energy if not instructed to do so.


Conservation of EnergyThe toy is wound up and speeding up as it moves up an incline.

A B C D E





Conservation of EnergyThe toy is wound up and speeding up as it moves up an incline.

A B C D E


A B C D E


The model should show:- Kinetic energy decreases.- Gravitational potential energy increases, it can be proportional to the changes in heights.- Elastic energy decreases.- No internal energy at first stage, internal energy never decreases.- Internal energy increases.

Accept:- Still elastic energy at the fifth stage.- Some gravitational potential energy at the first stage.- Some kinetic energy at the first stage.- Students do not include internal energy if not instructed to do so.


Conservation of EnergyA ball is held above the ground, and then is dropped so it falls straight down. (Restrict your analysis to the ball being in the air, BEFORE it hits the ground.)

A B C

Gravitational Potential EnergyElastic EnergyKinetic EnergyInternal Energy(Dissipated to Heat & Sound)A

B

C

The students are given small whiteboards and markers. They can be instructed to work in groups or alone. As they work, the teacher circulates the room and asks the student to discuss their energy pie charts. Afterward, a student can be asked to stand and share how they drew their energy pie diagrams and why. Other students can share how and why they completed their diagrams differently.


Conservation of EnergyA ball is held above the ground, and then is dropped so it falls straight down. (Restrict your analysis to the ball being in the air, BEFORE it hits the ground.)

A B C


A

B

C


The model should show:- The first stage has 100% gravitational energy, the second stage has roughly 66%, the third stage has none.- The first stage has no kinetic energy, the third stage has roughly 3-4 times as much as the second stage.- No internal energy at first stage, internal energy never decreases.- The first stage has no internal energy, it increases in the second and third stages, it can be proportional to the speed.

Accept:- Quantity of kinetic and internal energy is not the same as the example.- Internal energy increases, but not more as the speed increases.- Students do not include internal energy if not instructed to do so.


Conservation of EnergyA baseball is thrown up in the air and then falls back down. Place velocity vectors beside each corresponding baseball in the drawing, and draw an energy storage pie for each lettered position.

A B C D E





Conservation of EnergyA baseball is thrown up in the air and then falls back down. Place velocity vectors beside each corresponding baseball in the drawing, and draw an energy storage pie for each lettered position.

A B C D E



The model should show:- First and fifth stages have the same quantity of gravitational potential energy.- Fourth stage has roughly 50% of the gravitational potential energy as third stage.- Second stage has roughly 80-90% of the gravitational potential energy as third stage.- Third stage has no kinetic energy.- No internal energy at first stage, internal energy never decreases.- Internal energy increases in each stage.

Accept:- No gravitational potential energy at the first and fifth stages.- Students do not include internal energy if not instructed to do so.


Conservation of EnergyAn object rests on a coiled spring, and is then launched upwards.

A B C

Gravitational Potential EnergyElastic EnergyKinetic EnergyInternal Energy(Dissipated to Heat & Sound) A B C




Conservation of EnergyAn object rests on a coiled spring, and is then launched upwards.

A B C


A B C


The model should show:- First stage is 100% elastic energy.- Some kinetic energy in second stage, none in third stage.- About 30% more gravitational energy from second to third stage.- No internal energy at first stage, internal energy never decreases.- Internal energy increases.

Accept:- Some gravitational potential energy at first stage.- Quantity of kinetic, gravitational potential, and internal energy is not exactly the same in second stage of example.- Students do not include internal energy if not instructed to do so.


Conservation of EnergyA piece of clay is dropped to the floor.

A B C

Gravitational Potential EnergyElastic EnergyKinetic EnergyInternal Energy(Dissipated to Heat & Sound)A

B

C




Conservation of EnergyA piece of clay is dropped to the floor.

A B C


A

B

C


The model should show:- First stage has 100% gravitational potential energy, second stage has roughly 50%, third stage has none.- Third stage has 100% internal energy.- No internal energy at first stage, internal energy never decreases.- Second stage should have some kinetic energy and some internal energy.

Accept:- Quantity of kinetic and internal energy in second stage is not the same as example.- Students do not include internal energy in the second stage.


Conservation of EnergyA ball rolls to a stop on the floor.

A B C

Gravitational Potential EnergyElastic EnergyKinetic EnergyInternal Energy(Dissipated to Heat & Sound) A B C


The students continue to create energy pie charts for situations. As they work, the teacher circulates the room and asks the student to discuss their energy pie charts. Afterward, a student can be asked to stand and share how they drew their energy pie charts and why. Other students can share how and why they completed their charts differently.Image from:https://modelinginstruction.org/26

Conservation of EnergyA ball rolls to a stop on the floor.

A B C


A B C


The model should show:- First stage has 100% kinetic energy, second stage has roughly 25%, third stage has none.- First stage has no internal energy, second stage has roughly 75%, third stage has 100%.

Accept:- Second stage does not have the exact same quantities as example.


Conservation of EnergyA superball is dropped and bounces up and down. Draw a pie chart for each position of the ball shown. Why does the ball not bounce as high each time? Where does the energy "go?

A B C D E




Images from:https://modelinginstruction.org/http://deansomerset.com/wp-content/uploads/2011/11/tennis-ball-impact.jpg28

Conservation of EnergyA superball is dropped and bounces up and down. Draw a pie chart for each position of the ball shown. Why does the ball not bounce as high each time? Where does the energy "go?

A B C D E



The model should show:- 100% gravitational potential energy in first stage, roughly 75% in third, and roughly 50% in fifth stage.- No gravitational potential energy in second or fourth stages. - Elastic energy in the second and fourth stages, none in first, third, and fifth stages.- No internal energy at first stage, internal energy never decreases.- Internal energy increases, it should increase most and second and fourth stages.

Accept:- Internal doesnt increase from second to third stage, or fourth to fifth stage.

Images from:https://modelinginstruction.org/http://deansomerset.com/wp-content/uploads/2011/11/tennis-ball-impact.jpg

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Conservation of EnergyA moving cart slows slightly as it rolls toward a spring, and then comes to a stop by compressing the spring.

A B C


A B C




Conservation of EnergyA moving cart slows slightly as it rolls toward a spring, and then comes to a stop by compressing the spring.

A B C


A B C


The model should show:- First stage is 100% kinetic energy, roughly 75% at second stage, and none at third stage.- No elastic energy at first or second stage, but some at third stage.- No internal energy at first stage, internal energy never decreases.- Internal energy at second and third stages.

Accept:- Quantity of kinetic and internal energy is not exactly same as example in second stage.- Quantity of elastic and internal energy is not exactly same as example in third stage.- Internal energy does not increase from second to third stage.


Conservation of EnergyA truck being driven down the street.

A B C

Chemical EnergyGravitational Potential EnergyElastic EnergyKinetic EnergyInternal Energy(Dissipated to Heat & Sound) A B C

This final energy pie chart problem includes an additional challenge. Students will need to include chemical energy.



Conservation of EnergyA truck being driven down the street.

A B C

Chemical EnergyGravitational Potential EnergyElastic EnergyKinetic EnergyInternal Energy(Dissipated to Heat & Sound)

A B C


The model should show:- Kinetic energy is at each stage and it remains constant.- Chemical energy at first and second stages.- No internal energy at first stage, internal energy never decreases.- Internal energy increases at the second and last stages, it increases by roughly the same amount.

Accept:- No chemical energy at third stage.- Quantity of internal energy at second and third stages are different than example, but increase.


Conservation of Energy

A car on a roller coaster track, launched by a huge spring, makes it to the top of the loop.

This slide introduces Energy Bar Charts as a way to show the energy in a system at different stages. Students need to define the system. The center circle is to show energy transferred into or out of the system via work.



A car on a roller coaster track, launched by a huge spring, makes it to the top of the loop.

The spring transfersenergy into the system.NONE

These are two possible answers.

The model should show:- Total quantity of energy at the final position equals the total quantity of the energy at the initial position, plus any work done to and minus and work by the system.- The final position should have some kinetic and gravitational potential energy.

Accept:- Either elastic energy at the initial position, or work being done to the system, depending on how the system is defined.- Students use a different quantity of energy units.- Students do not include internal energy if not instructed to do so.

Images from:https://modelinginstruction.org/35


A car on a roller coaster track, launched by a huge spring, makes it to the top of the loop. The same car is launched by the spring, but it is only half way up the loop.

NONE

Instruct the students to complete the Energy Bar chart relative to the example above. As they work, the teacher circulates the room and asks the student to discuss their energy bar charts. Afterward, a student can be asked to stand and share how they drew their energy bar chart and why. Other students can share how and why they completed their charts differently.



A car on a roller coaster track, launched by a huge spring, makes it to the top of the loop. The same car is launched by the spring, but it is only half way up the loop.

NONENONE


The model should show:- Total quantity of energy at the final position equals the total quantity of the energy at the initial position, plus any work done to or by the system.- Four energy units used, they begin as elastic energy.- Quantity of gravitational potential energy is half in the second problem.- Quantity of kinetic energy is larger in the second problem.- Quantity of internal energy is smaller in the second problem.

Accept:- Students do not include internal energy if not instructed to do so.


Conservation of EnergyA moving car, moving up a hill, coasts to a stop up.

The students continue to create energy bar charts for situations. As they work, the teacher circulates the room and asks the student to discuss their energy bar charts. Afterward, a student can be asked to stand and share how they drew their energy bar chart and why. Other students can share how and why they completed their charts differently.


Conservation of EnergyA moving car, moving up a hill, coasts to a stop up.

NONE


The model should show:- Total quantity of energy at the final position equals the total quantity of the energy at the initial position, no work being done to or by the system.- Initial position should have some kinetic energy and no gravitational potential or elastic energy.- Final position should have some gravitational potential energy and no kinetic or elastic energy.

Accept:- No work being done to or by the system.- Students use a different quantity of energy units.- Students do not include internal energy if not instructed to do so.


Conservation of EnergyA load of bricks, resting on a compressed spring, is launched into the air.

The students continue to create energy bar charts for situations. As they work, the teacher circulates the room and asks the student to discuss their energy bar charts. Afterward, a student can be asked to stand and share how they drew their energy bar chart and why. Other students can share how and why they completed their charts differently.


Conservation of EnergyA load of bricks, resting on a compressed spring, is launched into the air.

The spring transfersenergy into the system.


The model should show:- Total quantity of energy at the final position equals the work done to and minus and work by the system.- Initial position should have no energy.- Work should be done to the system by the spring.- Final position should have some kinetic and gravitational potential energy, but elastic energy.

Accept:- Students use a different quantity of energy units.- Quantities of kinetic and gravitational potential energy at final position are different from example.- Students include internal energy unless instructed to not do so.


Additional Practice:Read p. 84 87# 6.9 6.14

The additional practice can be found in the Cambridge IGCSE Physics (Second Edition) written by David Sang.

More information about this coursebook can be found here:http://education.cambridge.org/as/subject/science/physics/cambridge-igcse-physics-%28second-edition%29/cambridge-igcse-physics-coursebook-with-cd-rom-%28second-edition%29

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Education

Period 3 - Conservation of Energy Practice